netdev - Re: [PATCH] net: phy: broadcom: Wire suspend/resume for BCM54612E

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Date: Wed, 1 Nov 2023 23:06:56 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Marco von Rosenberg <marcovr@...fnet.de>
Cc: Florian Fainelli <florian.fainelli@...adcom.com>,
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: phy: broadcom: Wire suspend/resume for BCM54612E

On Wed, Nov 01, 2023 at 10:42:52PM +0100, Marco von Rosenberg wrote:
> On Tuesday, October 31, 2023 1:31:11 AM CET Andrew Lunn wrote:
> > Are we talking about a device which as been suspended? The PHY has
> > been left running because there is no suspend callback? Something then
> > triggers a resume. The bootloader then suspends the active PHY? Linux
> > then boots, detects its a resume, so does not touch the hardware
> > because there is no resume callback? The suspended PHY is then
> > useless.
> 
> Hi Andrew,
> 
> thanks for your feedback. I guess a bit of context is missing here. The issue 
> has nothing to do with an ordinary suspension of the OS. The main point is 
> that on initial power-up, the bootloader suspends the PHY before booting 
> Linux. With a resume callback defined, Linux would call it on boot and make the 
> PHY usable.

Ah, so you rely on phy_attach_direct() calling phy_resume(phydev).

This seems an odd way to solve the problem. It was not Linux which
suspend the PHY, so using resume is asymmetric.

I think soft_reset() or config_init() should be taking the PHY out of
suspend.

	Andrew